Exact Duality in String Effective Action

TL;DR

This paper develops a new formulation of sigma-model duality transformations using the spin connection, revealing conditions under which this duality is an exact symmetry of the full string effective action, and generating new solutions.

Contribution

It introduces a spin connection-based approach to string duality, enabling the identification of exact symmetries including higher-order corrections.

Findings

Duality can be an exact symmetry of the full string effective action.

New string solutions can be generated via the duality transformation.

The approach simplifies the transformation rules for the spin connection and gauge fields.

Abstract

We formulate sigma-model duality transformations in terms of spin connection. This allows to investigate the symmetry of the string action including higher order $\alpha'$ corrections. An important feature of the new duality transformations is a simple homogeneous transformation rule of the spin connection (with torsion) and specifically adjusted transformation of the Yang-Mills field. We have found that under certain conditions this duality is a symmetry of the full effective string action in the target space, free of $\alpha'$ corrections. We demonstrate how the exact duality generates new fundamental string solutions from supersymmetric string waves.